The Health Aging and Body Composition Study (Health ABC) is a prospective community-based observational cohort study of 3075 healthy black and white men and women aged 70-79 residing in Pittsburgh, PA (n=1527) and Memphis, TN, (n=1548). The Health ABC study participants have currently been followed for more than 10 years. [unreadable] [unreadable] This project will use mRNA isolated from Health ABC participants in study years 6, 8, and 10 to systematically invetigate the correlation between the expression of a set of candidate biomarkers and differential blood cell counts.